1. Technical Field
The present invention relates to a photocurable ink composition, a recording method, and a recording apparatus. The invention also relates to a photocurable ink jet recording ink composition and an ink jet recording method.
2. Related Art
Various systems have been utilized as recording methods of forming images on recording media such as paper based on image data signals. Among them, an ink jet system is an inexpensive apparatus and directly forms an image on a recording medium by discharging an ink only on a necessary image area and therefore efficiently uses inks at low running cost. In addition, the ink jet system is low in noise and is therefore excellent as a recording method.
Recently, in the recording method of the ink jet system, a photocurable ink composition, which is cured by light irradiation, is used as an ink composition that can provide high water resistance, solvent resistance, abrasion resistance, etc.
For example, JP-T-2004-526820 discloses an ink jet ink that does not substantially contain water and/or any volatile solvent and contains at least one multifunctional (meth)acrylate monomer, at least one α,β-unsaturated ether monomer, at least one radical photopolymerization initiator, and at least one dispersible pigment. The content of the multifunctional (meth)acrylate monomer is 2 to 15 parts by weight based on 1 part by weight of the α,β-unsaturated ether monomer, the ink has a viscosity at 25° C. of less than 100 mPa·s, and the content of the α,β-unsaturated ether monomer in the ink is 1 to 30% by weight.
For example, JP-A-2008-19292 discloses a photocurable composition that contains a polymerizable compound (a), 0.1 to 15% by mass of a photopolymerization initiator and/or photoacid generator (b), and 0.001 to 5% by mass of at least one of fluorochemical surfactants, silicone surfactants, and fluoro-silicone surfactants (c), and has a viscosity at 25° C. of 3 to 18 mPa·s (d). The polymerizable compound (a) includes a polymerizable unsaturated monomer (e) having a primary skin irritation index (PII) value of 4.0 or less and a polymerizable unsaturated monomer (f) having a viscosity at 25° C. of 30 mPa·s or less each in an amount of 50% by mass or more. The polymerizable unsaturated monomer (e) and the polymerizable unsaturated monomer (f) may be partially or totally the same polymerizable unsaturated monomer.
For example, JP-A-2004-224841 discloses an active energy ray-curable composition containing prescribed vinyl ether group-containing (meth)acrylic esters (A), a 1,3-dioxolane ring and/or 2-oxo-1,3-dioxolane ring (B), and a photopolymerization initiator (C).
For example, JP-A-2008-179136 discloses a method of forming an image by applying an undercoating liquid containing 2-(2-hydroxyethoxy)ethyl acrylate, isobonyl acrylate, and a polymerization initiator onto an intermediate transcript, subsequently discharging an ink containing 2-(2-hydroxyethoxy)ethyl acrylate, isobonyl acrylate, a polymerization initiator, a pigment, a dispersant, and a surfactant onto the intermediate transcript, and then transferring the ink onto a recording medium.
Unfortunately, the ink jet ink described in JP-T-2004-526820, the photocurable composition described in JP-A-2008-19292, the active energy ray-curable composition described in JP-A-2004-224841, and the ink used in the image-forming method described in JP-A-2008-179136 cause problems of being inferior curing or occurrence of wrinkles on a coating film surface after curing (hereinafter, also referred to as “curing wrinkles”).
Furthermore, for example, Japanese Patent Nos. 3461501 and 3544658 disclose an active energy ray-curable ink jet printing ink or a reactive diluent composition composed of 2-(vinyloxyethoxy)ethyl acrylate or 2-(vinyloxyethoxy)ethyl methacrylate, 2-(hydroxyethoxy)ethyl vinyl ether as a polymerizable compound containing a hydroxyl group, a colorant, and a photopolymerization initiator.
For example, JP-A-2009-62541 discloses an ink jet ink containing at least one multifunctional (meth)acrylate monomer, at least one vinyl ether monomer, at least one radical photopolymerization initiator, and at least one dispersible pigment. The amount of the multifunctional (meth)acrylate monomer is 2 to 15 parts by weight based on 1 part by weight of the vinyl ether monomer, the content of the vinyl ether monomer is 1 to 15% by weight, and the content of the multifunctional (meth)acrylate monomer is 50 to 95% by weight.
For example, JP-T-2008-507598 discloses a radiation curable ink jet ink containing 25.8% by weight of hexanediol diacrylate, 4.6% by weight of an amine adduct of tripropylene glycol diacrylate, 2.3% by weight of 2-(2-ethoxyethoxy)ethyl acrylate, 2.5% by weight of alkoxylated phenoxyethyl acrylate, 3.7% by weight of 2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone, 3.2% by weight of 2-hydroxy-2-methylpropiophenone, 2.8% by weight of a mixture of trimethylbenzophenone and methylbenzophenone, 0.5% by weight of isopropylthioxanthone, 27.8% by weight of a cyan pigment dispersant, and 17.6% by weight of 2-(2-vinyloxyethoxy)ethyl acrylate.
For example, JP-A-2010-157706 discloses a curable composition for photo-imprint composed of 9.5% by mass of a monofunctional acrylic monomer (benzyl acrylate), 9.8% by mass of 2-(2-vinyloxyethoxy)ethyl acrylate, 47.3% by mass of a difunctional acrylic monomer (neopentyl glycol diacrylate), 19.4% by mass of a trifunctional acrylic monomer (trimethylol propane triacrylate), 1.0% by mass of a photopolymerization initiator, 2.0% by mass of an antioxidant, 10.0% by mass of a coupling agent, and 1.0% by mass of a surfactant.
Unfortunately, the inks described in Japanese Patent Nos. 3461501 and 3544658, JP-A-2009-62541, JP-T-2008-507598, and JP-A-2010-157706 have problems of being inferior in at least any of curing properties, adhesion, and photopolymerization initiator solubility.